The present invention relates to a papermaking mold, with which pulp molded articles with excellent surface smoothness and a satisfactory appearance can easily be produced, and a method of producing pulp molded articles using the mold. The invention also relates to a papermaking mold, with which pulp molded articles of any desired shape can easily be produced, and a method of producing pulp molded article using the mold. The invention also relates to an apparatus for producing pulp molded articles.
A drying mold used to dry a water-containing molded article formed by a pulp molding method has passages for discharging water or steam out of the mold.
When a conventional drying mold is used, however, the projected traces of the passages are transferred to the surface of a molded article to impair the appearance of the molded article; some shapes of molded articles are liable to scratches when removed from the drying mold; or pulp fiber tends to adhere and accumulate in the passages so that the drying mold needs frequent cleaning.
According to JP-A-5-279998, a pulp component is deposited on a papermaking net, which is pressed by a pressing mold made of an elastic material and formed into the shape of a container and then hot-pressed by a press having the shape of a container to produce a molded article.
The pressing mold used in the above-described method is used only to press the pulp component and cannot be used for papermaking or dewatering. Therefore, the steps of from papermaking to shaping require a separate member for shaping, i.e., the above-mentioned pressing mold, in addition to a member for papermaking and dewatering. This makes the production process complicated. Further, it is difficult to make molded articles of complicated shape, for example, those having an undercut.
When the container precursor obtained by pressing the pulp component by the pressing mold is transferred to the press, the container precursor, being in intimate contact with the papermaking net, has poor releasability, which reduces production efficiency, and may be damaged in some manners of removing from the mold.
JP-A-7-223230 discloses a molding method using a mold composed of an inner mold and an outer mold, the inner mold having attached thereto a flexible membrane capable of being inflated to form substantially the same contour as the inner shape of a desired molded article, wherein a molding material is squeezed between the inner mold and the outer mold, and a fluid pressure is applied from a fluid pipe between the flexible membrane and the inner mold to inflate the flexible membrane. According to this method, however, because a fluid is supplied from one place between the flexible membrane and the inner mold, it is difficult to cause the molded article to elongate uniformly by pressing with the inflated flexible membrane. It tends to follow that the molded article suffers from cracks or thickness unevenness.
Apart from these methods, known apparatus for producing pulp molded articles include the one described in JP-A-8-232200, which is an apparatus for making a pulp molded article having a multilayer structure. The apparatus disclosed comprises a papermaking mold which reciprocates linearly and a plurality of feedstock tanks which are arranged along the travel of the papermaking mold.
In this apparatus, the papermaking mold successively travels starting from the first feedstock tank to carry out papermaking and completes papermaking at the final feedstock tank. After the molded article built up on the papermaking mold is shifted to a drying step, the papermaking mold returns to the first feedstock tank and repeats the reciprocating motion. Accordingly, the papermaking mold needs time to return back to the starting position, which means that a single papermaking cycle requires an extended time. This cannot be seen as highly productive.
In this apparatus, the molded article after the papermaking step is transferred directly to a drying mold composed of an outer mold and an inner mold, where the article is dewatered by suction. The shaped article before dewatering which is wet enough to be easily deformable must be handled, and positioning accuracy is hard to secure in transferring into the drying mold, unavoidably resulting in poor molding accuracy. In producing thin-walled articles, in particular, it often happens that the molded articles are broken when transferred. Thus, the apparatus is not applicable to production of thin-walled articles.
Additionally, it is impossible with the papermaking mold and the inner and outer molds for drying used in the above apparatus to make deep containers whose side walls stand at right angles or nearly right angles, containers whose neck is narrower than the body, and containers having a so-called undercut.
Accordingly, an object of the present invention is to provide a papermaking mold with which a pulp molded article having excellent surface smoothness and a satisfactory appearance can easily be obtained and a method of producing such a pulp molded article.
Another object of the present invention is to provide a papermaking mold with which a pulp molded article having a complicated shape can conveniently be obtained and a method of producing such a pulp molded article.
Still another object of the present invention is to provide a papermaking mold from which a molded article is removed satisfactorily to produce molded articles with good productivity and a method of producing a pulp molded article.
Yet another object of the present invention is to provide a papermaking mold with which a pulp molded article of desired shape can easily be produced without developing cracks or thickness unevenness and a method of producing a pulp molded article.
A further object of the present invention is to provide a papermaking mold with which a pulp molded article can be produced efficiently with high molding accuracy and a method of producing a pulp molded article.
A furthermore object of the present invention is to provide an apparatus for producing a pulp molded article with which a high production efficiency can be achieved.
A furthermost object of the present invention is to provide an apparatus for producing a pulp molded article with which deep containers whose side walls stand at right angles or nearly right angles, containers whose neck is narrower than the body, and containers having a so-called undercut can easily be produced.
The present invention accomplishes the above objects by providing a papermaking mold for producing a pulp molded article which comprises a core of prescribed shape made of an elastically deformable material and having a plurality of holes for fluid passage which interconnect the outside and the inside thereof and a fluid-permeable material covering the outer surface of the core, the fluid-permeable material being capable of securing passages for a fluid in its thickness direction even when pressed and deformed.
The present invention accomplishes the above objects by providing a papermaking mold for producing a pulp molded article which comprises a flat papermaking plate having a plurality of through-holes at a prescribed interval, an upper plate disposed above the papermaking plate, a number of cores each fixed to the lower side of the upper plate and fitted into each of the through-holes from the upper side of the papermaking plate, and a fluid-permeable material covering the lower side of the papermaking plate, wherein
the papermaking plate has a plurality of holes for fluid passage which are open on the lower side thereof and interconnect the lower side and the inside of the papermaking plate,
the core is made of an elastically deformable material and has a plurality of holes for fluid passages interconnecting the outside and the inside thereof,
the upper plate is connected to the papermaking plate via a number of connecting guides in such a manner as to slide vertically and, as the upper plate slides, the core fixed to the lower side of the upper plate is removably fitted through each through-hole of the papermaking plate, and
the fluid-permeable material is capable of forming fluid passages in the thickness direction thereof even when pressed and deformed.
The present invention accomplishes the above objects by providing a papermaking mold for producing a pulp molded article which comprises a core that is a rigid body of prescribed shape having a plurality of holes for fluid passage interconnecting the inside and the outside thereof, a core holding member that is positioned under the core and is made of an elastically deformable material, and a mesh member which closely covers the outer surface of the core holding member, wherein
the core holding member has formed therein interconnecting holes open on the outer surface thereof, the interconnecting holes linking up with the holes for fluid passage formed in the core when the core holding member is disposed under the core.
The present invention accomplishes the above objects by providing a papermaking mold for producing a pulp molded article which comprises a main body made of an elastically deformable material and having inside a cavity of prescribed shape and a plurality of holes for fluid passage that lead the cavity to the outside, an expanding and contracting member which slides within the cavity in the height direction of the main body, and a mesh member closely covering the outer surface of the main body, wherein
the expanding and contracting member has interconnecting holes which interconnect the inside and the outside thereof, and
when the expanding and contracting member is slid down, the cavity is pushed wider to expand the main body through elastic deformation, and the interconnecting holes and the holes for fluid passage connect up with each other in at least the state before the sliding.
The present invention accomplishes the above objects by providing a method of producing a pulp molded article which comprises:
immersing a papermaking mold having interconnecting passages that interconnect the outside and the inside thereof and capable of elastic deformation in a pulp slurry, sucking up the water content in the pulp slurry from the outside to the inside of the papermaking mold through the interconnecting passages to form a pulp layer on the surface of the papermaking mold,
fitting the papermaking mold having the pulp layer formed thereon into an impression of a female mold that is shaped in conformity with the contour of a molded article in such a manner that the base of the pulp layer is the first to come into contact with the bottom of the female mold,
pressing and deforming the papermaking mold in conformity with the shape of the impression thereby to transfer the shape of the impression onto the pulp layer and to discharge the water content of the pulp layer outside the papermaking mold through the inside of the papermaking mold.
The present invention accomplishes the above objects by providing a method of producing a pulp molded article which comprises:
immersing a papermaking mold having interconnecting passages that interconnect the outside and the inside thereof and capable of elastic deformation in a pulp slurry, sucking up the water content in the pulp slurry from the outside to the inside of the papermaking mold through the interconnecting passages to form a pulp layer on the surface of the papermaking mold,
fitting the papermaking mold having the pulp layer formed thereon into an impression of a female mold, the impression being shaped in conformity with the contour of a molded article, the upper side of the impression being covered with an extensible sheet that is fixed to the periphery of the impression, while deforming the extensible sheet by extension so that the base of the pulp layer is brought into contact with the bottom of the impression via the extensible sheet, and
pressing and deforming the papermaking mold in conformity with the shape of the impression thereby to transfer the shape of the impression onto the pulp layer to make a molded article.
The present invention accomplishes the above objects by providing a method of producing a pulp molded article which comprises:
immersing a papermaking mold having interconnecting passages that interconnect the outside and the inside and capable of expansion and contraction in a pulp slurry, with the papermaking mold being adjusted to a prescribed size, to form a pulp layer on the surface of the papermaking mold,
contracting the papermaking mold to contract the pulp layer to a prescribed size,
fitting the contracted pulp layer into the impression of a female mold composed of a set of splits, and
expanding the pulp layer as fitted into the impression by a prescribed means to press the pulp layer onto the inner wall of the impression for dewatering.
The present invention accomplishes the above objects by providing an apparatus for producing a pulp molded article which comprises a papermaking mold having a papermaking part, a papermaking station having a liquid tank containing a pulp slurry, a dewatering station where a pulp layer formed on the outer surface of the papermaking part of the papermaking mold is dewatered by pressing, and a transfer station where the pressed and dewatered pulp layer is transferred to a subsequent station, wherein
the papermaking part of the papermaking mold has a core which is capable of elastic deformation under pressing,
the dewatering station has a dewatering female mold having an impression in which the papermaking part of the papermaking mold is to be fitted, the impression of the dewatering female mold being made larger than the shape of the papermaking part of the papermaking mold, and
the papermaking station, the dewatering station, and the transfer station are arranged in this order on prescribed positions in an orbit, and the papermaking mold moves from station to station to revolve in the orbit.